The motorhome vin# tells what year the motorhome was built, what year the frame and engine are, and what year the motorhome is. The frame does not have a vin#. The frame has a serial #. The year of the motorhome is determined by the year it was built and the year model info in the vin # provided by the manufacture. The frame year is not used to determine the model year. You sure you didn't buy a 2004 model and not a 2005 model? If you really want to know do as I did, call the manufacture and give them the vin# so they can look it up to tell you the year model. They will also send you a letter telling you what year model it is. Then you can show the letter to the DMV as proof of model year.